Instructions
Enter the house beside the Pokémon Center in Eterna City. Talk to the Underground Man inside; he will give you the Explorer Kit.
Go outside and use the Explorer Kit to be transported to the Underground. Walk around the winding passageways and tunnels.
Tap the touch screen on the Nintendo DS to send out a pulse of sonar. Check the map on the upper screen for treasure locations buried in the walls.
Walk to one of the areas indicated on the map by a yellow sparkle and press the "A" button on the walls. If you receive a message that the wall is bulging slightly, choose the option to dig into it. This takes you into a mini game in which you choose between a pick axe or hammer to chisel away at the rock to locate the treasures inside. Tap the bottom screen with the stylus to remove rubble from treasure. If you completely unearth an item, it is yours to keep.
Play with others in the Underground using the Wi-Fi function of the Nintendo DS. If you and another player are standing close to each other while in the Underground, you will be able to interact in the same Underground maze.